A conventional Otto engine operates in four strokes a) Induction stroke in which the piston moves towards the crankshaft and sucks a mixture of fuel and air into the cylinder through an open inlet valve or valves b) Compression stroke in which the inlet valve(s) close(s) and the mixture is compressed as the piston moves away from the crankshaft, then ignition of the combustible gases followed by c) the power stroke as the piston is pushed down by the expanding gases preforming work, and d) the exhaust stroke as the piston moves away from the crank shaft and the exhaust valve or valves are opened so that the burnt mixture is pushed out of the cylinder. The cylinder is now ready for the next cycle.
Many different arrangements of cylinders around a single crank shaft have been proposed. The most conventional engines have multiple pistons arranged in various configurations e.g. in line, in V formation, horizontally opposed to each other, and radially.
In more recent times the moving parts of engines have become lighter which reduces problems due to lack of balance and has allowed the development of high speed (r.p.m.) engines.
For example in U.S. Pat. No. 3,710,767, DE 3921 581 there is disclosed four stroke internal combustion engines which have double acting pistons. By “double acting” is meant pistons performing a power stroke in either direction of movement of the piston. The different engines disclosed have a disadvantage in that their pistons are rigidly fixed to a coaxial piston rod which in turn is connected to the crankshaft through a conventional connecting rod. This produces a larger heavier engine which have more large moving parts and extended sumps.
The present invention seeks to produce internal combustion engines having better power to weight ratio.